With known rotating heat exchangers of this kind, peripheral seals are provided between the rotor and the housing enclosing it at the front end face of the rotor and at the rear end face of the rotor, by means of which peripheral seals the exit of air from the airflow flowing through the rotor into the housing is to be prevented. Since the rotor rotates with respect to the housing enclosing it, considerable leaks between the rotor on the one hand and the housing on the other hand always occur during the operation of a rotating heat exchanger of this kind, which can lead to air from the airflows flowing through the rotor exiting from the rotor. This can lead to the supply air for a room made available by the rotating heat exchanger becoming undesirably contaminated.